Among the technologies that allow computers and/or other network devices to form a local area network (LAN), Ethernet has become the dominant networking technology and is standardized in the IEEE 802.3 family of standards. The Ethernet standard has evolved over time so that different variants of the Ethernet protocol now exist to support higher bandwidth, improved media access controls, different physical media channels, and/or other functionalities. For example, IEEE 802.3 now has variants covering speeds (or transmission rates) ranging from 10 Mbit/s, 100 Mbit/s, 1 Gbit/s, to 10 Gbit/sand even higher, and has variants that govern physical channels such as coaxial cables, fiber-optics, and unshielded/shielded twisted-pair cables.
In systems and devices that communicate using the Ethernet protocol, an interface exists between the media access control (MAC) layer and the physical layer to facilitate the exchange of information between the two layers. This interface is referred to as a media independent interface (MII). The term MII also refers to a specific type of media independent interfaces, in addition to referring to the entire genus. As used herein, the terms “media access interface” and “MII” will refer to the entire genus of such interfaces, unless otherwise noted. Examples of MIIs include Attachment Unit Interface (AUI), MII, Reduced MII, Gigabit MII (GMII), Reduced GMII, Serial GMII (SGMII), Quad SGMII (QSGMII), 10GMII, and Source Synchronous Serial MII (S3MII).
Designing media independent interfaces presents significant engineering challenges. Examples of these challenges include reducing or minimizing electromagnetic interference (EMI), power consumption, pin count, and circuit board complexity. Accordingly, there is a need for more efficient MII designs. Also, there is a need for new designs to be configurable for backward compatibility with existing MII protocols, to simplify manufacturing.
Like reference numerals refer to corresponding parts throughout the drawing figures and specification.